Heat sealed ruffled article



L.. C. HOSFIELD HEAT SEALED RUFFLED ARTICLE June 5, 1951 Filedrknec. 7,194e A 3 Sheets-Sheet 1 Q. Sv

INVENTOR LEE C. HOSFIELD BY ATTORNEY June 5, .1951 L. c. HOSFIELD HEATSEALED RUFFLED ARTICLE 5 Sheets-Sheet 2 Filed Dec. 7, 1946 INVENTOR LEEc. HosFlELD BY ATTORNEY June 5, 1951 L. c. HosFlELD 2,555,409

HEAT SEALED RUFFLED ARTICLE Filed Dec. 7, 194s a sneetssheet s i I l IINVENTOR LEE C. HOSFIELD ATTORNEY Patented June 5, 1951 HEAT SEALEDRUFFLED ARTICLE Lee C.. Hosfield, Bennington, Vt., assignor, by

mesne assignments, to Union Carbide and Carbon Corporation, acorporation of New York Application December 7, 1946, Serial No. 714,832

12 Claims.

This invention relates to novel unitary .heatsealed ruiiies and ruliedarticles made from thermoplastic dielectric materials, and to a novelprocess and apparatus for making such unitary ruiiles by spot-weldingtogether successive folded-over portions of rufiied films, sheets,fabrics or other sheet-like elements of thermoplastic dielectricmaterials and, if desired, concurrently spot-welding successivefolded-over portions of the latter articles to another sheet, lilm,fabric or other sheet-like element made from the same or otherthermoplastic dielectric material.

A large variety of articles such as raincoats, aprons, umbrellas, windowcurtains, shower curtains, dry goods Sundries and the like now are beingmade from thermoplastic resinous dielectric materials. In themanufacture of such articles it is common practice to unite the marginsof two or more films by sewing the margins together, using thread ofsuitable material. Such operations involve the repeated puncturing f thesheeting by the fabricating needles at closelyspaced points, therebyweakening the material at and adjacent the seam. Moreover, the seamproduced is stiff and incapable of yielding when subjected to stretchingforces, so that sudden stresses sometimes tear the thread from thesheeting or break the thread after only a slight elongation of thefilms. This method of fabrication is not satisfactory, particularly forarticles strength, durability, or imperviousness to Iwater or otherliquids and gases is required.

For the purpose of providing a stronger article, processes have beendeveloped whereby sheets or lms to be united have flat overlappingmargins pressed together to form a seam while being heated to suitabletemperatures. Heat and pressure are applied by means of heatedcooperating pressure rolls to form a continuous welded seam.

In recent years the so-called electronic method of heating has assumedimportance as a source of the welding heat. Opposed pressure rolls serveas rotating electrodes in a high frequency electric circuit` Thethermoplastic dielectric materials, while continuously pressed betweenthe electrodes, are subjected t0 a high frequency electric field,thereby being softened and welded together. Continuous narrow weldedareas which readily are visible are thus formed. Such methods requi-rethat the sheets to be united are of uniform thickness and free fromwrinkles, etc.

There are a wide variety of articles made from thermoplastic dielectricmaterials which, to be satisfactory for the intended use, require theaflixing lto a sheet, fil-m or fabric made of or conwhere taining acoating of a thermoplastic dielectric material, of ruiiles of the sameor an equivalent material. Among such articles may be mentioned windowcurtains, shower curtains, apons and other articles of wearing apparel,shelf and table decorative strips and covers, and the like. There alsois a demand for unitary ruffled articles made from such dielectricmaterials.

It is highly important that such ruffled articles have an attractiveappearance and be of a uniform construction. The rui'lied structure mustbe strong, tough, permanent, and sufficiently elastic to yield whensubjected to tensile or to puncturing forces Without being injured ordestroyed. The present invention is concerned with such a ruled articleand with the novel method and apparatus for its production.

Among the more important objects of the invention are 'the fol-lowing:to provide a novel unitary ruiiied article made entirely ofthermoplastic ,dielectric material; to provide an unpcrioratedheat-sealed ruffle or ruled article of dielectric material, and onewhich is free from restricting threads of dissimilar material; toprovide a ruflied article wherein the sides of each ruilied area formedin a dielectric thermoplastic material are permanently united toeachother and to an adjacent ruilied area, and, if desired, to a basesheet, by a plurality of spot welds to provide a ruiiled compositearticle wherein each individual fold of the ruffle is of uniform sizeand is spot welded to the base sheet and to an adjacent fold at one ormore spaced points of limited area; to providesuch a unitary heat-sealedruilied article which can be elongated more than of its original lengthwithout rupturing the ruilled structure or the seam; to provideheat-sealed ruffles having stronger lbond-s between the base sheet andthe ruiiie and greater resilience along the line of the ruille thanruffled articles made by sewing with thread; to provide novel ruilieclarticles wherein repairs to the ruilies can be made merely byspot-welding without loss of the ruiiied material; to provide in novelmanner for the production at high rates of thermoplastic sheet-likearticles having permanently'united therewith strong welded-on ruffles,uniform and pleasing in appearance, and having good physical properties;to provide a novel process and apparatus for continuously producingthermoplastic articles having welded-on ruiiles while preventing injuryto the ruliled material; to provide a novel process and apparatus forwelding ruliles of a dielectric material upon a base sheet of such amaterial by means of a high frequency electric field, while inhibitingarcing at the electrodes and burning of the material; and to provide innovel manner for the continuous spot-uniting of ruiiled sheets, films,fabrics or the like made from or containing dielectric thermoplasticmaterials with other sheets, films, or fabrics made from or containingthe same or other thermoplastic dielectric material, either plasticizedor unplasticized, or made from paper, cloth and like materials, coatedwith such a dielectric material.

The invention has especial utility for the production of strong,permanent, yielding ruiles and ruffled articles having elasticproperties made from such plasticized thermo-plastic materials as thecellulose esters and ethers, such as cellulose acetate, viscose,regenerated cellulose and ethyl cellulose; vinyl resins, such as thepolyvinyl chlorides, the polyvinyl acetates, copolymers of vinylchloride and vinyl acetate, polyvinylidene chloride resins, polyvinylalcohol resins, polyvinyl acetal resins, polymethacrylate resins, andcopolymers of vinyl halides and acrylic compounds, such as coploymers ofvinyl chloride with acrylonitrile, with acrylic acid, and with theacrylic acid lower alkyl esters; copolymers of butadiene with styreneand with acrylonitrile; and resinous reaction products of a diamine anda dicarboxylic acid.

A preferred form of the novel articles of the invention generallyinvolves a base sheet, film, fabric or other sheet-like element of athermoplastic synthetic resin or other dielectric material which ispermanently united by one or more series of spaced spot welds with asheet-like element of the same or other thermoplastic dielectricmaterial having the form of a continuous succession of interconnectedfolds or rues of uniform size and shape. The respective sides of eachfolded area are permanently united with each other, with a side of thenext adjacent folded area, and with one or more layers of the base sheetby means of at least one spot weld, and preferably two welds, covering asmall portion of each such folded area. Since the individual folds arenot secured by restricting non-elastic sewed threads, the entire body ofthe welded ruie or the composite article is free to yield under tensionand to elongate or stretch, the extent of such elongation beingdependent upon the character of the material from which the sheet-likeelements are made, the number, area and character of the spot welds, andupon other factors. In the case of articles made from sheets of vinylresins, such as those produced by the copolymerization of a vinyl halidewith a vinyl ester of a lower aliphatic acid-e g., a vinylchloride-vinyl acetate copolymer containing between '70% and 95% of thechloride in the polymer-the heat-sealed ruflied article can be elongatedmore than 90% of its original length without rupturing the welded seamand, when tension is released, will regain its original length. The bondbetween the base sheet and the ruffled sheet is from 60 to 90 strongerthan that secured in the same article by sewing with thread.

Since each of the folds is unrestricted by threads, the peak of eachfold is free to pucker outwardly from the base sheet and to give to theruffled article a uniform, pleasing appearance. rIhe folded areas arenot noticeably deformed by the welding heat and pressure used.

If, when such a ruffled article is subjected to excessive stress, one ormore of the spot welds fails, the ruffles still are held in place andthe appearance and the strength of the ruflied struc- 4 ture arepreserved by the remaining spot welds adjacent those which failed.

The novel ruffled articles are made, in accordance with a preferred formof this invention, by a novel process and apparatus which forms a rapidsuccession of similar ruiiles or folds of the desired size and shape ina sheet-like element of suitable dielectric material and, as rapidly aseach such ruiiie or fold is formed, the sides of such fold arepermanently spot-welded to each other and to a surface of a nextadjacent fold, and preferably to one or more layers of a suitablesheet-like base element, at from one to two or more spaced points oflimited area in such fold. The welding is effected by the use oflocalized heat and pressure. The heat is produced locally in thematerial at each successive folded area by bringing such areas betweentwo electrodes to which a high frequency electric current of suitablevoltage is applied, as hereinafter more particularly described.

In the accompanying drawings wherein are illustrated certain preferredforms of the invention,

Fig. 1 is a diagrammatic view of one form of apparatus of the invention,parts being omitted;

Fig. 2 is a side elevation of one form of heatsealing machine showingthe electrodes, electrode reciprocating mechanism, and associated parts,parts being broken away, and other parts being omitted;

Fig. 3 is a schematic wiring diagram of another high frequency heatingcircuit and associated parts;

Fig. 4 shows diagrammatically the relationship between the actuating camfor the reciprocating electrode and the rotary tuning device of Fig. 3;

Fig. 5 illustrates two alternate forms of tuning stubs or impedancematching means for the high frequency heating circuit;

Fig. 6 is a fragmentary plan view of a folding and indexing blade forforming the ruffles;

Fig. '7 is a perspective fragmentary view of a reciprocatable electrodeand operating stem;

Fig. 8 shows one preferred form of ruffled composite article of theinvention;

Fig. 9 shows another form of the ruffled composite article;

Fig. l() shows a unitary ruliied heat-sealed strip reinforced by a.folded-over end margin; and

Figs. ll and 12, respectively, show other forms of composite ruiliedarticles of the invention.

Referring to Figs. 1 and 2 of the drawings, the apparatus comprises anoperating head H which conveniently may be mounted on a table T,generally similar to the operating head and table of the standard typeof sewing machine. Secured to the lower end of a member I I mounted onthe head H for longitudinal reciprocation are one or more upperelectrodes i3 adapted to cooperate with corresponding stationary lowerelectrooles I5 aligned therewith and formed on an electrode plate Isecured below the table top in suitable manner and insulated from thelatter by a plate Il of a dielectric material such as polystyrene. Arider IS secured to member II slides in a groove in a guide member I2and prevents turning of the member I I.

For passing a high frequency electric current through a plurality oflayers of one or more sheets of thermoplastic organic dielectricmaterial while in the space between the electrodes to heat such.material to a welding temperature, the electrodes are in a highfrequency electric circuit which comprises an oscillator or 'asse-109generator I9 or other source of high frequency electric current. Oneterminal of the high frequency output line is grounded through a line2|). The other terminal is connected with the stationary electrode plateI6 through a coaxial transmission line, the outer conductor 2|a of whichterminates in the outer tube 23 of a tuning stub 26 such as shown inFig. 5. The inner conductor 2| terminates in a coaxial inner rod 23a ofthe stub 26. A coaxial variable capacitance 24 connects the tube 23 androd 23a within the said tube. ITube 23 is grounded through line 25. Ashort circuiting membel` 25a fixes the length of the short circuitedstub. The electrode I3 is grounded through a flexible strap 21.

For reciprocating each electrode I3 in a fixed path toward and from acorresponding stationary electrode I5, a standard electric motor 29,equipped with a magnetic brake for instantaneous starting and stoppingand of a type commonly used on industrial sewing machines, drives arotatable shaft 3| through pulleys 33 and and V-belt 31. Shaft 3| drivesan upper shaft 39 through pairs of beveled gears 48, 48, and 4I, 4|, andvertical shaft 43. Secured upon one end of shaft 39 is a cam plate 45having a groove in one face providing a cam surface 4'3. A cam follower49 is mounted for rotation on a pin secured upon a follower block 5|.The latter is secured for vertical adjustment upon re- J ciprocatablerod and has rigidly connected therewith the electrode or electrodes I3.By means of a set screw 52 in block 5| the latter can be secured at aselected point along the rod and thus determine the pressure appliedupon I the thermoplastic material by each 'electrode I3 when the latteris in the lowermost position during a spot-welding operation. Acompression spring 53, operatively interposed between a pin or flange onrod I| and a fixed part of the operating head H, continuously exerts adownward pressure upon the reciprocating rod during operation andprevents backlash.

For feeding a strip or sheet of dielectric material M from `a source vofsupply thereof and for forming a succession of rules or folds thereinadjacent the welding or heat-sealing zone a pair of feeder rollsincluding an idler roll 55 and a roll 56 driven by a motor 51 draw asheet of such material from a supply roll 58. The sheet then is directedaround a dancer roll 6| and idler rolls 62, 62 and v82" and thencebetween a fixed margin fold-over guide 63. It then is movedintermittently to the welding zone between the electrodes I3, I5, bymeans of a ruflling mechanism R. The dancer roll 6| is rotatably mountedupon an end of a rod 59 which is pivoted about a fulcrum 8D. Mounted onthe end of rod 59 opposite roll 6| is an adjustable counter- Weight, anda mercury switch 64 of well-known type having terminals connected in theelectrical circuit driving motor 51. vThe arrangement is suc-h that whenthe roll 8| is in the position shown in full lines in Fig. 1, the switch84 vcuts off current to motor 51, and that when roll 6| is in theposition shown in broken lines the switch closes the circuit and drivesmotor 51. Thus, any differences between the rate of unwinding ofmaterial from the supply roll and the rate demands of the ruillingmechanism are equalized.

For feeding a sheet M, with or without a base sheet or film B, ofthermosplastic dielectric material between and past the electrodes at awelding or heat-sealing zone, a resiliently mounted presser foot 61cooperates with a vertically and laterally movable feed dog 69 whilepressingly engaging the sheets interposed therebetween. The feed dog hasa serrated surface area adapted intermittently to contact the undersideof the ruffled sheet or the composite sheet B and move the same to theleft in Fig. 1 away from the welding zone. Thereafter the feed dog isdepressed and withdrawn from contact with such sheet and moved to theright toward the welding zone. For effecting such feed of the sheet orsheets the presser foot 61 is secured to a rod 68 mounted on the head Hfor movement toward and from the feed dog 59. An adjustable compressionspring 1e presses the foot 51 upon the sheets lying upon the feed dogunder a selected pressure. A cam member 1| pivoted on the head Hcooperates with a member 12 secured to rod 68 for raising and loweringthe rod 38 and for locking it in raised position. For effectingintermittent movement of the feed dog and the sheets lying between itand the presser foot in a direction from the welding zone, as showndiagrammatically in Fig. l, the feed dog 59 is secured to an arm 13which is connected with a crank 14 secured upon the shaft 3|. The crankarm 13 is pivoted upon an end of a rocker arm 15, the other end of whichis pivotally connected with a fixed support. In the form shown in Fig.2, the feed dog is secured to a plate 13 which has an end pivotallysecured to the arm 15. A cam member 11 mounted on shaft 3| cooperateswith a cam groove in the plate 16 during rotation of the shaft. The cammember is pivotally connected with arm 15 through arm 13. Duringoperation of motor 29 the rotation of shaft 3| and crank 14 causesthefeed dog 55 successively (l) to rise vertically and engage the sheet Mcr B, (2) to move to the left to index the ruflled article, then (3) toretract downwardly from the sheet and (fi) to move toward the rightwhile disengaged from the latter; and to repeat this cycle of motionsfor every rotation of shaft 3 I. The movement of feed dog 69 is timed sothat it advances the ruiiied article to the left a selected distancejust before each forward movement of the fold-indexing mechanism to bedescribed.

For forming in sheet M a succession of ruilies of uniform size andspacing at a uniform rapid rate, a crank plate 19 secured upon shaft 39is operatively connected, by means of a rod 3U and a clevis 8| with alever arm 82 secured upon a rocker shaft 33 suitably supported on theoperating head. When shaft 33 is rotated the rocker shaft 83 oscillatesthrough a selected arc, depending upon the position of clevis 8| alongthe arm 82 maintained by means of a, clevis pin cooperating with one ofthe apertures in arm 82. Secured to an end of rocker shaft 83 is a leverarm 84 which supports an adjustable folding and indexing blade 85. Thelatter is pivoted upon ears formed on the lever arm 34, and has a rearflange portion cooperating with a spring 86 carried by that arm to urgethe blade downwardly against the sheet of material under a regulatedtension. The forward end of the blade has a serrated margin and hastherein slots 87 (see Fig. 6) adapted to accommodate the electrodes I3,i3. The arrangement is such that blade 85 is held in retracted pcsitionto the right (see Fig. 2) away from the electrodes I3 during the weldingpart of each cycle of operation, and then advances to the left duringthe part of the cycle when electrodes |3, I5 are held apart, therebymoving fresh sheet material into position between the spaced electrodesand forming therein a fold or pleat. A

'stationary serrated blade 85 prevents retraction of the sheet M whenblade 85 is retracted, and prevents folds being formed in sheet B. Afolder guide 63 adjacent the folder guide 63 folds over a margin of thebase sheet as it moves to the welding zone.

The fold or pleat produced can be varied in size, and the number offolds or pleats per inch can be regulated by the adjustment of thelength of stroke of the arm 84. To increase or to reduce the number offolds per inch, clevis SI is connected with arm 32 at a point furtherfrom or nearer to shaft 83, respectively. Preferably the adjustment issuch that from six to eight rues r folds per inch are produced, althougharticles having from four to twelve folds per inch readily are made.However, the ruffled areas should be at least one-sixteenth of an inchin width in order to insure the spot-welding of each ruilie at one ormore spaced points even in instances where some stretching of thematerial results from action of the folder blade 85 or of the feederfoot 69.

The actual welding portion of each cycle of operation, during which theelectrodes I3, I5, or respective pairs thereof, exert pressure upon thefolded-over portions of the ruiiie material, and upon the base sheetwhen present, constitutes about three-fourths of the cycle and isgoverned by the shape of the cam surface 41. The welding tion, thevariable capacitance 24 and the interconnecting lines define a matchingcircuit having impedance that can be varied to accommodate various loadimpedances and to provide maximum power transfer to the work.

Tuning stubs of the type shown in Fig. are particularly useful asmatching sections when employing frequencies of around 100 to 200 ormore megacycles. Such tuning stubs are in the form of a coaxialtransmission line connected with the high frequency generator. The outerconductor of the coaxial line is a brass tube 99 and the inner conductoris a brass rod 9|. Two brass sleeves 3, 94, serve as terminals of thetransmission line, one sleeve sliding upon the outer conductor 99 andthe other sliding on the inner conductor 9I. The length of the shortcircuited portion is adjusted by means of a brass disc 95 which slidesalong the inside of the outer tube but also contacts the inner rod 9I.The length of the load end is adjusted by sliding the respectiveterminals 93, 94 along the tube and rod.

In another form of tuning stub illustrated in Fig. 5, the movableshorting disc 95 is replaced by a fixed snorting disc 96 (shown indotted lines in Fig. 5), so that the length of the short circuited stubis fixed. 'I'he points of the transmission line termination at the tubeand rod also are fixed. A coaxial variable capacitance 9'1 (shown indotted lines) is set within tube 90 and is connected across theconductors 90, 9|.

Fig. 3 illustrates schematically a form of circuit particularly useiulwith frequencies of around 50 to 100 megacycles. It effectively preventsarcing at each electrode I3 as the latter is rapidly withdrawn from thewelding zone, by throwing 8 the high frequency circuit out of resonancefrom a time just prior to the withdrawal of electrode I3 from pressingcontact with the work until after the electrode is in contact withanother ruffie in the next succeeding cycle of operation.

If desired, the circuit can be detuned in various ways during suchperiod of each cycle to accomplish this purpose. In the form of theinvention shown in Figs. 3 and 4, the circuit comprises a high frequencygenerator I9 having one terminal 2i! grounded and having its otherterminal connected in series through line 22 with a fixed inductance|05, a variable condenser V and the lower electrode plate I6. A line |06having therein a fixed inductance IIJI connects line 22 to ground. Thecondenser V has segmental rotor plates 99 subtending an arc of 90,mounted upon a rotatable shaft IIJU having an electrically insulatedportion Illa and driven from shaft 3| through a pair of bevel gears IUI. The condenser has fixed plates |92 with cutaway segmental portionssomewhat greater than the width of segmental plates 99, and preferablysubtending an arc of 120.

Fig. 4 more clearly indicates the function of the detuning variablecondenser, wherein it is shown in full lines in the position duringwhich a fold is being formed and moved into position between theelectrodes and the high frequency circuit is out of resonance. Oneposition of the plates 99 during the welding stage of each cycleindicated in broken lines. The use of this condenser permits the use ofoptimum voltage during the welding stage of each cycle, while limitingthe voltage during the balance of the cycle to one insufficient to causearcing or burning of the materials.

Fig. 4 also illustrates the general shape of the rotary cam 47 which, inconjunction with spring 53, controls the reciprocation of rod II, andthe period of its dwell in a position with electrode I3 in weldingposition. As shown, this cam and the cam follower 49 raise and lowerelectrode I3 in a vertical pattern during one-fourth of a cycle, andthen, with the aid of spring 53, hold the electrode in pressure contactwith the rufiied material during the balance of each cycle. Throughcorrelation of the timing of the respective movements of the cam 41, thefolder blade and the feeder foot 69, the successful production of weldedruffled articles having eight ruffies per inch, each ruffle beingconcurrently spotwelded in two zones, has been accomplished at the rateof 34 feet per minute. This corresponds to the production of 3,264single welds per minute or, when using two pairs of electrodes, 6,528welds per minute.

i In performing the process using the apparatus of Figs. l and 2, theleading ends of the respective base sheet B and ruffle element M areplaced in mutual contact above the feeder foot 69 and between theelectrodes, and motor 29 is started. The motel1 concurrently actuatesthe feeder foot 69, reciprocates the electrode I3, and oscillates thefolder blade 85. Each cycle of operations, dur ing a revolution of cam41, is as follows: While electrodes I3 are raised from the work thepresser foot 5l cooperates with feed dog 59 and holds the severalthicknesses of sheets while the ruiller blade scuifs in the ruiile sheetM a fold perpendicular to the direction of feed. Thereafter, while theblade holds the fold in place the upper electrodes I3 descend upon thefold and hold it, under pressure from spring 53, while the blade 85 isretracted. The radio frequency voltage impressed upon the electrodescauses current to flow through the two walls of each of the one or morelayers of material forming the folded area in sheet M and through eachlayer of the base sheet B, softening the material and spot-welding theseparts together at one or more, and preferably two, small spaced weldingzones defined by the electrodes, the degree of welding heat dependingupon the voltage across the electrodes. The electrodes i3 then areraised, thereby releasing the welded sheets. The feed dog and presserfoot then advance the work to make room at the welding zone for the nextrume. The parts are so synchronized that the ruiiler blade 85 is inretracted position while the weld is being made, and that the feed dog69 has completed its action advancing each welded before the ruiilerblade forms the next succeeding ruffle.

The apparatus of Figs. 3 and 4 function similarly to that of Fig. 1,with the exception that immediately prior to retraction of theelectrodes I3 from the welding position the high frequency heatingcircuit is detuned by movement of plates 99 of the variable condenser Vinto the position shown in full lines in Fig. 4, thereby reducing thevoltage between the electrodes and preventing arcing at the electrodes,The circuit remains in the detuned condition until the blade 85 hasformed another fold and each electrode I3 has moved into pressingContact with the upper surface of the newly folded area.

Variations in the rate of application of energy to the material duringthe different stages of each cycle/of operations also can be effected bymodulating the oscillator tube in the high frequency generator, or inany other well-known manner.

One preferred form of spot-welded ruffled article is illustrated in Fig.8. In that figure the two sides of each layer of material forming eachof the ruiiles or folded areas F in the sheet M, one side of each layerforming an adjacent folded area F, and one or more layers of the basesheet B are permanently united by two spaced spot welds W of anysuitable shape and size. The material at the unwelded portions of eachfolded area is unrestrained and free to assume a rounded shapethroughout the remainder of the length of each fold. All portions of theruflied thermoplastic article are free to yield or stretch under anytension exerted either longitudinally or laterally of the rows of spotwelds formed. By employing a folder guide 63 for folding over the marginof sheet M, and/or a folder guide B3 for folding over a margin of sheetB (see Fig. l) each spot weld units from four to six or more thicknessesof the thermoplastic material, as shown in Fig. 8. Preferably, thefolded-over marginal portions of both the sheets M and B are ofsufficient depth that each of the welds formed in a ruiiie unites thesame number of layers of dielectric material as the other weld or welds.

The tiny but tough spot welds enhance the appearance of the ruffledarticle while at the same time providing adequate strength, andpreserving in such article the normal resilience of the thermoplasticmaterial from which the sheeting is made, unrestrained by extraneousmaterials having properties differing therefrom, such as non-yieldingthreads. All portions of each sheet M and B are entirely free fromperforations and other sources of weakness.

Fig. 9 illustrates a form of the invention wherein each of one or morelayers of a sheet-like element of a dielectric material has formedtherein a succession of closely-spaced folded areas throughout its widthand wherein each of one or more layers of a relatively narrow sheet-likebase of a dielectric material is permanently united with each of saidfolded areas by means of one spot weld located midway between themargins of the sheet-like element. By the use of a somewhat widersheet-like base, two or more spot welds can be made in each folded area.By using a sheet-like base and sheet-like element of different colors,attractive color effects and the effect of sewing or gathering withcolored threads are secured at each spot weld due to the color of thebase showing through to the surface of said sheet-like element. Thus, aruching or doubleruifle effect is secured in a unitary article. Ifdesired, two or more narrow, longitudinallyspaced, sheet-like bases maybe united with the sheet-like element.

Permanent unitary rniiies may be made from single sheet-like elements.Thus, in one form of the invention illustrated in Fig. 10, by using onlythe sheeting M, the latter is provided with a ruiiledmargin wherein eachfold is spot-welded in place, the welding uniting the two sides of eachruiiled or folded area to. each other and to a side of an adjacentfolded area. The resultant product may be stored or used as such, orlater may be united with a second sheet or film such as the sheet B, ina separate spot-welding or other operation.

Fig. 1l illustrates another form of ruflie which can be produced inaccordance with the invention. The ruifles are produced -by well-knownfolder attachments now in use on standard sewing machines. Here each ofthe one or more rows of spot welds W unites portions of the sheet M atfolded areas through three or more thicknesses of the dielectricmaterial. Each folded area consists of a relatively nat mid-portion II0, two inwardly sloping end portions Ill, and two outwardly flaringportions II2, the respective portions being welded together by spacedspot welds arranged in one or more rows. A base sheet B may bespot-welded to the folded sheeting, as in the case of the article shownin Fig. 8.

Fig. 12 illustrates still another form of ruffled article made with theuse of the invention in connection with standard ruiling equipment. Herethe base sheet B and the ruffled sheet M are spot-welded at one or morespaced points W lying between adjacent ridges.

It will be understood that the invention is not limited to the ruffledarticles specifically described, nor to the particular form of theprocess and apparatus for making the same described. On the contrary,numerous modifications are possible within the scope of the appendedclaims, whereby a unitary permanent ruffled article is made, andespecially one wherein the sides of each ruffled area of each of one ormore sheets are spot-welded together and to an adjacent folded area ofsuch sheet at one or more spaced points, and, if desired, to one or morebase sheets, and wherein the remainder of the sheet or sheets at eachruiiied area is substantially unconned and is free to yield or stretchunder stress.

Either or both of the sheet-like elements of thermoplastic dielectricmaterial may be replaced by a sheet-like element of a non-thermoplasticfibrous material in the form of a woven, knitted, felted or other fabricimpregnated or coated with a thermoplastic dielectric material, and theruiiles formed and spot-welded in the mann-er hereindescribed. Thus, awoven or knitted fabric made from yarns of cotton, wool, silk, glass orthe like may be impregnated and/or coated in Whole or in part With a lmor body of a vinyl resin or other thermoplastic dielectric materialhereinbefore mentioned. Such composite article then is converted intothe form of a Welded ruffle or, if desired, is concurrently ruled' andsecured to another element of a thermoplastic dielectric material or ofa non-thermoplastic material coated with a thermoplastic dielectricmaterial by Welding in the manner described. Also useful as thesheet-like elements and/or bases are the composite fabrics made fromyarns formed by compositing filaments or fibers of a non-thermoplasticmaterial such as cotton, etc., With filaments or fibers of a plasticizedthermoplastic dielectric material.

The term sheet-like element and similar expressions used in the claimsare intended to designate sheets, lms, Webs, batts, and Woven, knittedand other fabrics Which are relatively small in one dimension,

I claim:

l. A unitary permanent rufed article comprising a sheet-like element ofa thermoplastic dielectric material, a portion of such element within aselected area thereof being folded on itself to form a succession ofinterconnected rullies, the material forming the respective sides ofeach folded area being permanently united by at least one spot Weldproduced by heat and pressure in a limited zone Within each such foldedarea.

2. A unitary permanent ruliled article comprising a sheet-like elementof a thermoplastic dielectric material, said element having formedtherein within a selected area a succession of folded areas, therespective sides of the element forming each such folded area beingpermanently united to each other and to a side of the next adjacentfolded area by means of at least one spot weld formed by heat andpressure, the major portion of each folded area being unrestrained andfree to yield under the action of stretching and puncturing forces.

3. A unitary permanent ruffled article comprising a sheet-like elementof a thermoplastic dielectric material having at least one marginalportion folded upon itself to form a multi-layer folded-over portion, aselected area Within such folded-over portion being further folded toform a succession of interconnected folded areas embracing the saidfolded-over portion, the layers of material forming the respective sidesof each folded area being permanently united to each other by at leastone spot Weld produced by heat and pressure in a limited Zone lyingwholly Within such folded area.

4. A unitary permanent ruilled article comprising a sheet-like elementof a thermoplastic dielectric material having at least one marginalportion folded upon itself to form a multi-layer folded-over portion, aselected area Within such folded-over portion being further folded toform a succession of closely-spaced interconnected folded areas Withinsaid folded-over portion, the layers of material forming the respectivesides of each folded area being permanently united to each other and toa side of a next adjacent folded area by at least one spot weld producedby heat and pressure.

5. A unitary permanent ruffled article comprising a sheet-like elementof a thermoplastic dielectric material, and permanently united With atleast one layer of such element at least one layer of a sheet-like baseof a thermoplastic dielectric material, said sheet-like element having12 a succession of closely-spaced folded areas, the said element andsaid base being permanently united at each of said folded areas by meansof at least one spot Weld, the major portion of each folded area beingfree to yield under the action of stretching and puncturing forces.

6. A unitary permanent ruffled article comprising at least one layer ofa sheet-like element of a thermoplastic dielectric material havingformed therein a succession of closely-spaced folded areas, and at leastone layer of a relatively narrow sheet-like base of a thermoplasticdielectric material, the said element and said base being permanentlyunited at a mid-point of each such folded area by means of at least onespot Weld, each folded area and the base being free to yield under theaction of stretching and puncturing forces.

7. A unitary permanent ruffled article comprising a sheet-like elementof a thermoplastic dielectric material, and permanently united with atleast one layer of such element at least one layer of a sheet-like baseof a thermoplastic dielectric material, said sheet-like element havingat least adjacent one margin thereof a succession of folded areas, thesaid element and said base being permanently united at points betweenadjacent folded areas by means of at least one spot Weld, each suchfolded area being free to yield under the action of stretching andpuncturing forces.

8. A unitary permanent ruffled article comprising a sheet-like elementof a thermoplastic dielectric material, and permanently united with atleast one layer of such element at least one layer of a secondsheet-like element of a thermoplastic dielectric material having atleast adjacent one margin thereof a succession of folded areas, therespective sides of each such folded area being permanently united toeach other and to the rst-named sheet-like element by means of at leastone spot Weld lying Wholly within each such folded area and formed byheat and pressure, the major portion of each folded area being free toyield under the action of stretching and puncturing forces.

9. A unitary permanent ruffled article comprising a sheet-like elementof a thermoplastic dielectric material having permanently united with atleast one layer of such element at least one layer of a secondsheet-like element of a thermoplastic dielectric material havingadjacent one margin thereof a succession of folded areas, the sides ofeach such folded area being permanently united to each other, to a sideof the next adjacent folded area and to the first-named sheet-likeelement by means of at least one spot Weld covering only a portion ofthe width of such folded areas, the major portion of each such foldedarea being free to yield under the action of stretching and puncturingforces.

10. A unitary permanent ruined article comprising a sheet-like element,at least one surface of which element comprises a thermoplasticdielectric material, at least a portion of such element Within aselected area thereof being folded on itself to form a succession ofinterconnected ruffles, the material forming the respective sides ofeach folded area being permanently united by at least one spot Weldconfined Within a limited Zone within each such folded area.

11. A unitary permanent ruffled article comprising a sheet-like element,a surface of which includes a thermoplastic dielectric material, andpermanently united with at least one layer of such element at least onelayer of a sheet-like base having a surface whichincludes athermoplastic dielectric material, said sheet-like element havingtherein a succession of closelyspaced folded areas, the said element andsaid base being permanently united at each of said folded areas by meansof at least one spot weld covering only a portion of the width of eachsuch folded area, the major portion of each folded area being free toyield under the action of stretching and puncturng forces.

12. A unitary permanent ruied article comprising a sheet-like element ofa thermoplastic dielectric material, and permanently united with suchelement at least one layer of a sheet-like base of a thermoplasticdielectric material having a color other than that of said sheet-likeelement, such element having a succession of closely spaced foldedareas, the said element and said base being permanently united at eachof the said folded areas by means of at least one spot weld having across-section substantially less than the width of the folded area,whereby the color of the said base shows through to the surface of saidsheet-like element at said welded areas, the major portion of eachfolded 'area being free to yield under the action of stretching andpuncturing forces,

LEE C. HOSFIELD.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name 'Date 1,049,680 Dahl Jan. 7, 19131,094,707 De Voe Apr. 28, 1914 1,571,654 Tiedemann Feb. 2, 19261,698,275 Plaat Jan. 8, 1929 2,121,013 Brown June 21, 1938 2,143,844Daller Jan. 17, 1989 2,158,762 Phelan May 16, 1939 2,253,077 KiernerAug. 19, 1941 2,322,298 Johnston June 22, 1943 2,367,725 Lindh Jan. 23,1945 2,892,598 Lewis Jan. 8, 1946 2,432,412 Hacklander Dec. 9, 1947FOREIGN PATENTS Number Country Date 573,518 Great Britain NOV. 23, 1945OTHER REFERENCES Hoyler: An Electronic Sewing Machine, reprint from theAugust 1943 issue of Electronics (7 pages).

1. A UNITARY PERMANENT FUFFED ARTICLE COMPRISING A SHEET-LIKE ELEMENT OFA THERMOPLASTIC DIELECTRIC MATERIAL, A PORTION OF SUCH ELEMENT WITHIN ASELECTED AREA THEREOF BEING FOLDED ON ITSELF TO FORM A SUCCESSION OFINTERCONNECTED RUFFLES, THE MATERIAL FORMING THE RESPECTIVE SIDES OFEACH FOLDED AREA BEING PERMANENTLY UNITED BY AT LEAST ONE SPOT WELDPRODUCED BY HEAT AND PRESSURE IN A LIMITED ZONE WITHIN EACH SUCH FOLDEDAREA.